Outdoor navigation is widely deployed thanks to the development of various global-navigation-satellite-systems (GNSS), e.g., Global Positioning System (GPS), GALILEO, and the like.
Recently, there has been a lot of focus on indoor navigation. This field differs from the outdoor navigation, since the indoor environment does not enable the reception of signals from GNSS satellites.
One solution for indoor navigation includes a Time-of-Flight (ToF) measurement method. The ToF may be defined as the overall time a signal propagates from a first station, e.g., a user (“client”) mobile device, to a second station, e.g., an access point (AP), and back to the first station. A distance between the first and second stations may be calculated based on the ToF value, for example, by dividing the ToF value by two and multiplying the result by the speed of light.
In one example, the mobile device may be in the indoor location, in which the mobile device is unable to receive signals from the GNSS satellites. The mobile device may use the ToF measurement in the indoor location. However, when the mobile device moves out of the indoor location, the ToF measurement may become not accurate, and using the signals from the GNSS may be more beneficial. In some cases, the mobile device may continue to use the ToF measurement, until the ToF measurement is not available, for example, even if the ToF measurement is not accurate.